As a means of regulating heat, vehicle seats have already been proposed, which have at least one supporting face designed to provide support for an occupant, this supporting face being made from a material susceptible to phase changes and exhibiting phase transition temperatures contained which a range between lower and upper limits of 15 and 37.degree. C. (see, for example, the article entitled "thermal foam keeps seats and headliners warm in winter, cool in summer", Automotive & Transportation Interiors, October 1998, p. 16).
The known seats of this type therefore have a self-regulated surface temperature which, when the seat ceases to be occupied, is automatically maintained for a certain period of time within the range of phase transition temperatures of the phase-change material. As a result, if the user of the seat gets back into the seat within a relatively short time of having left it (1 hour, for example), his initial contact with the seat will be pleasant.
However, once the phase transition of the phase-change material is complete, the surface temperature of the seat follows the ambient temperature of the vehicle. Consequently, if the user of the seat gets back into the seat some time (2 hours, for example) after having left it, the climatic conditions in certain instances may cause the surface temperature of the seat to shift to values which make the initial contact of the user with the seat unpleasant or even painful.
As a matter of fact, the pleasant contact temperatures which can be supported for a long period of time are in the range of between 28 and 32.degree. C., for example.